What can I try next? Engine won't start.

mattd

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My Craftsman lawnmower has a Briggs & Stratton Platinum Series 725 engine.

The engine just will not start. I began troubleshooting with my regular yearly maintenance:

1. Removed any old gas from previous season
2. Remove oil from previous season
3. Changed spark plug
4. Sprayed carb cleaner into carburetor
5. Replaced air filter
6. Added new oil
7. Added new gas

My lawn is so small that my mower only gets used for 3 or 4 hours total in a season. Some would say that it's overkill for me to replace the oil, filter, and plug each season.

Tried it out, it ran for about a half of a second before shutting off. So then I tried the following:

1. Removed fuel line and flushed it out
2. Cleaned out fuel tank
3. Removed carburetor and cleaned it out thoroughly

Tried it again, it did the same thing, ran for about a second then quit. So I tried to run it again, this time it didn't start at all.

I had hunch that it was just starting, and burning off the carb cleaner then stopping. So I sprayed a little into the carburetor and tried it again. Again it ran for a second and then stopped. After a bit of playing around with it, I discovered that I could spray some carb cleaner into the carburetor, start it, then immediately start spraying more into the carburetor and it would continue to run. So it runs off the carb cleaner, but for some reason it's not running off of the gas.

I don't know what's causing the problem or what I should do next, my knowledge of small engines is pretty limited.

Any help would be appreciated.

Thanks,
Matt
 

cpurvis

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That's because it isn't getting any gas to run on.

Your carburetor probably needs a thorough cleaning. Spraying carburetor cleaning into the throat of a carburetor doesn't clean much of anything. There are tiny passageways in the carburetor which meter the fuel flow and deliver it to the right place in the throat of the carb so that low pressure air can draw the right amount out of the float chamber, and mix it with the air to form a combustible mixture that the engine can run on.

The good news is, most Briggs carburetors are relatively simple to work on, but they must be disassembled and cleaned and any worn out parts replaced.

The even better news is, most Briggs carburetors are cheap and a new one can be bought just about anywhere or online. Take off the old, put on the new and be done with it.

And don't use ethanol gas in it!

p.s.--If you're only using your mower 3 or 4 hours per year, it might be easier and cheaper to have a lawn service take care of your yard. Or get a push-type reel mower! No engine at all!
 

mattd

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Hi cpurvis,

Thanks for this advice.

I only spray into the throat for a quick cleaning, because the mower doesn't get used much. After this failed to fix the problem, I did disassemble the carburetor and cleaned it thoroughly along with the fuel lines and tank.

The carburetor didn't appear to be worn or damaged which leads me to believe this may not be the problem.

Maybe it's time to get a smaller electric mower, this one was convenient at the time, it was on clearance and cost me less than $150, originally over $400.
 

cpurvis

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I didn't think about an electric mower but that would probably be a good choice. I still like the reel mower. No motor of ANY sort to go bad. It's powered by your muscles and your muscles are powered by peanut butter sandwiches and the like.
 

mattd

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Thanks again for your help. I've dropped it off at a local repair shop. Even if I decide not to keep it, I can still get it fixed up and probably donate it to someone with a bigger lawn.
 

8thborn

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Please let me know what they say was the issue. I have the same motor on a Husqvarna. I replaced the carburetor, spark plug, and magneto, and it still will not crank. It acts like it is not getting fuel, but it is a new carb. Maybe if I put a Honda sticker on it that will help.
 

mattd

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8thborn,

This is a pretty busy time of the year for the shops in my area, so first thing that they told me was that it would take a week and a half for them to look at it. I'm hoping to have it back by Friday, but you never know.

I'll let you know what the issue is when I find out.
 

mattd

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So, I got the mower back lastnight. They told me that the main jet was damaged and wasn't letting enough gas get through. I haven't tried it out yet to see how it runs, it's been raining for the last three days. Will try it when the weather dries up a bit.
 

8thborn

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I dropped my mower offyesterday at an authorized Briggs dealer since Husqvarna's warranty does not cover engines, transmissions, or normal wear items (this pretty much is anything that us not an engine or transmission).

They told me a week or more also. Of course I did not purchase from them. I won't make that mistake again.

Thanks for the update. I am awfully curious if they tell me one of my new parts was no good.
 
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